Washer fluid warming device

ABSTRACT

A warming device capable of quickly increasing a temperature of a washer fluid with a relatively-low current, warming a relatively-large volume of washer fluid, and further retaining a washer fluid in a warmed state for some time after a power supply is turned off is provided. A warming device includes a structure in which a small heating chamber is housed in an inner space of a heat-retaining hot fluid storage chamber and an electric heater is housed in an inner space of the small heating chamber. The heat-retaining hot fluid storage chamber has a heat-insulating structure. The small heating chamber has a moderate thermal conductivity. A washer fluid fed from a washer tank is supplied to the small heating chamber through the heat-retaining hot fluid storage chamber, warmed by the heater and ejected from a washer nozzle.

The disclosure of Japanese Patent Application No. JP2011-005277 filed on Jan. 13, 2011 including the specification, drawings, claims and abstract is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a device arranged between a washer tank and a washer nozzle in a washer apparatus on board a vehicle, the device warming a washer fluid via an electric heater and being configured so as to be capable of quickly increasing a temperature of a washer fluid with a relatively-low current, warming a relatively-large volume of washer fluid, and furthermore, retaining a washer fluid in a warmed state for some time after a power supply being turned off, enabling reduction of power required for increasing the temperature of the washer fluid when the power supply is turned on next time.

2. Description of the Related Art

For washer fluid warming devices, there have been provided, e.g., those that use engine waste heat (Japanese Patent Laid-Open No. 2002-264779), and those that use an electric heater (Japanese Utility Model Laid-Open No. 6-27391).

A washer fluid warming device is particularly expected for use for frost removal in a cold winter; however, those that use engine waste heat have the problem of requiring long time to warm a washer fluid from engine starting. Meanwhile, those that use an electric heater require a large current (40 amperes or more) for quickly increasing the temperature of a washer fluid, causing problems such as overusing a battery already weakened by a low temperature and requiring, e.g., a large relay having thick electric wires and large contacts as well as transistor devices, resulting in a cost increase.

The present invention has been made in view of the aforementioned points, and an object of the present invention is to provide a washer fluid warming device capable of quickly increasing a temperature of a washer fluid with a relatively-low current, warming a relatively-large volume of washer fluid, and furthermore, retaining a washer fluid in a warmed state for some time after a power supply is turned off, enabling reduction of power required for increasing the temperature of the washer fluid when the power supply is turned on next time.

SUMMARY OF THE INVENTION

The present invention provides a washer fluid warming device arranged between a washer tank and a washer nozzle in a washer apparatus on board a vehicle, the washer fluid warming device warming a washer fluid sent in from the washer tank and sending the washer fluid out to the washer nozzle, the device including: a heat-retaining hot fluid storage chamber including a wall having a heat-insulating structure in which a vacuum layer is provided between an inner wall and an outer wall and including an inner space into which the washer fluid flowing out of the washer tank flows as a result of a washer pump being driven; a small heating chamber including a wall having a thermal conductivity higher than that of the wall of the heat-retaining hot fluid storage chamber, being housed in the inner space of the heat-retaining hot fluid storage chamber, and further including an inner space into which the washer fluid in the heat-retaining hot fluid storage chamber flows as a result of the washer pump being driven; and an electric heater housed in the inner space of the small heating chamber, the electric heater warming the washer fluid in the small heating chamber, wherein the inner space of the heat-retaining hot fluid storage chamber is set to have a size capable of accommodating a volume of washer fluid that is larger than a volume of washer fluid that can be accommodated by the inner space of the small heating chamber; and wherein the warmed washer fluid flowing out of the small heating chamber is supplied to the washer nozzle as a result of the washer pump being driven.

According to the present invention, upon power being supplied to the electric heater, a washer fluid in the small heating chamber can be warmed and ejected from the washer nozzle. The small heating chamber accommodates a volume of washer fluid that is smaller than a volume of washer fluid that can be accommodated by the heat-retaining hot fluid storage chamber, and thus, the temperature of the washer fluid in the small heating chamber can quickly be increased without using a large current. When the washer fluid is not ejected, the washer fluid in the heat-retaining hot fluid storage chamber can be warmed by means of thermal conduction via the wall of the small heating chamber. Since the heat-retaining hot fluid storage chamber has a heat-insulating structure, the washer fluid can be retained in a warmed state for some time after a power supply is turned off, enabling reduction of power required for increasing the temperature of the washer fluid when the power supply is turned on next time.

In the present invention, it is possible that: the heat-retaining hot fluid storage chamber includes an opening that provides communication between an outer space and the inner space thereof; the small heating chamber with the electric heater housed therein is attached to a lid that occludes the opening; and the small heating chamber is inserted into the inner space of the heat-retaining hot fluid storage chamber from the opening and thereby housed in the inner space of the heat-retaining hot fluid storage chamber and the opening is occluded by the lid. Consequently, a simple configuration can be provided, enabling easy assembly. Also, it is possible that: the lid includes a washer fluid inflow channel that allows the washer fluid to flow from the outside into the heat-retaining hot fluid storage chamber, a washer fluid outflow channel that allows the washer fluid in the small heating chamber to flow out to the outside, and an electric wire leading channel that allows an electric wire for supplying power to the electric heater to be led to the outside. Consequently, the necessity for the washer fluid inflow channel, the washer fluid outflow channel and the electric wire leading channel to be formed in the heat-retaining hot fluid storage chamber can be eliminated, providing a simple configuration and thus enabling easy assembly.

In the present invention, it is possible that: the small heating chamber is formed in a tubular shape extending in a vertical direction; the washer fluid warming device further includes a plate-shaped movable throttle lid housed in the inner space of the small heating chamber; the electric heater has a stick-like shape and is arranged along a central axis of the tubular small heating chamber; the movable throttle lid includes a central hole, and the electric heater is inserted through the central hole and arranged so that the movable throttle lid can ascend/descend along the electric heater, and upon the movable throttle lid being pushed up by the washer fluid flowing in from a lower portion of the inner space of the small heating chamber, the movable throttle lid makes the washer fluid on an upper side of the movable throttle lid flow out of the small heating chamber, and upon the inflow of the washer fluid being stopped, the movable throttle lid descends by its own weight and/or a spring force, and during the descent, the washer fluid on a lower side of the movable throttle lid is moved to the upper side of the movable throttle lid via at least any one of a gap between an inner face of the small heating chamber and the movable throttle lid, a gap between an outer face of the electric heater and an inner face of the central hole of the movable throttle lid, and a void formed within a face of the movable throttle lid. Consequently, when a washer fluid is ejected from the washer nozzle, the washer fluid warmed on the upper side of the movable throttle lid in the small heating chamber, which is to be supplied to the washer nozzle, and the washer fluid flowing in from the lower portion of the small heating chamber, which is not warmed yet, can be prevented from being mixed, as a result of the movable throttle lid functioning as a partition, enabling the warm washer fluid to be ejected from the washer nozzle.

In the present invention, it is possible that a bottom of the tubular small heating chamber is occluded by a plate material in which a throttle port is formed, through which the washer fluid in the inner space of the heat-retaining hot fluid storage chamber flows into the inner space of the small heating chamber. Consequently, it is possible to prevent a warmed washer fluid in the small heating chamber from flowing out from the lower portion of the small heating chamber. Furthermore, in the present invention, it is possible that the washer fluid warming device further includes a washer fluid flow passage in which the washer fluid flows into the inner space of the heat-retaining hot fluid storage chamber from an upper portion of the heat-retaining hot fluid storage chamber and descends in the inner space of the heat-retaining hot fluid storage chamber, and the washer fluid that has descended flows into the inner space of the small heating chamber from a lower portion of the small heating chamber and ascends in the inner space of the small heating chamber. Consequently, it is possible to provide a favorable flow of a washer fluid in the warming device. Furthermore, in the present invention, the heat-retaining hot fluid storage chamber and the small heating chamber can be formed in, for example, respective tubular shapes concentric to each other. Consequently, the warming device can have a compact structure, and thus can be installed in a narrow space such as an engine room of a vehicle.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A and 1B are diagrams illustrating a first embodiment of a warming device according to the present invention, which are a transparent front view and a transparent plan view of an inside of the warming device, respectively;

FIGS. 2A and 2B are a transparent front view and a transparent plan view of a heat-retaining hot fluid storage chamber in the warming device in FIG. 1A, respectively;

FIGS. 3A and 3B are a transparent front view and a transparent plan view of a lid of the warming device in FIG. 1A, respectively;

FIGS. 4A and 4B are a transparent front view and a transparent plan view of a sealing rubber (O-ring) to be attached to the lid in FIG. 3A, respectively;

FIGS. 5A and 5B are a transparent front view and a transparent plan view of a small heating chamber in the warming device in FIG. 1A, respectively;

FIGS. 6A and 6B are a transparent front view and a transparent plan view of a lower lid in the warming device in FIG. 1A, respectively;

FIGS. 7A and 7B are a transparent front view and a transparent plan view of a movable throttle lid in the warming device in FIG. 1A, respectively;

FIG. 8 is a diagram illustrating an electrical system and a washer fluid feeding system where the warming device in FIG. 1A is added to an existing washer apparatus;

FIG. 9 is a schematic diagram illustrating an operation of the warming device in FIG. 1A;

FIG. 10 is a table of results of a temperature increase test using a prototype of the warming device in FIG. 1A, which indicate changes in temperature of water in the small heating chamber after start of power supply to the heater;

FIG. 11 is a table of results of a temperature increase test using a prototype of the warming device in FIG. 1A, which indicate changes in temperature increase (increase amount of temperature) from an initial temperature of water in the heat-retaining hot fluid storage chamber;

FIG. 12 is a chart indicating results of a heat-retaining characteristic test using a prototype of the warming device in FIG. 1A; and

FIG. 13 is a diagram illustrating a second embodiment of a warming device according to the present invention, which is a transparent front view schematically illustrating the inside of the warming device.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment

A first embodiment of the present invention will be described. FIGS. 1A and 1B to 7A and 7B are transparent views of the inside of a warming device 10 according to the present embodiment. FIGS. 1A and 1B illustrate an assembled state of the warming device 10, and FIGS. 2A and 2B to 7A and 7B illustrate respective components of the warming device 10 (the scales of the diagrams are not the same). The warming device 10 is installed in, e.g., an engine room of a vehicle in such a manner that the warming device 10 is stood upright as illustrated in FIG. 1A. In FIG. 1A, the warming device 10 has a structure in which a cylindrical small heating chamber 14 is concentrically housed in an inner space 13 of a cylindrical heat-retaining hot fluid storage chamber 12 and a round bar-shaped electric heater (hereinafter “heater”) 16 is concentrically housed in an inner space 15 of the small heating chamber 14. The heater 16 and the small heating chamber 14 are concentrically attached to a lower face of a lid 30, the small heating chamber 14 with the heater 16 housed therein is inserted into the inner space 13 from an upper opening 26 of the heat-retaining hot fluid storage chamber 12, and the lid 30 is firmly screwed onto an upper portion of the heat-retaining hot fluid storage chamber 12, thereby providing an integrated configuration in their entirety. A washer fluid is fed from a washer tank 72 (FIG. 8) to the inner space 13 of the heat-retaining hot fluid storage chamber 12 through a hose 54, and flows into the inner space 15 of the small heating chamber 14 through throttle ports 60 at a lower end face of the small heating chamber 14, and is warmed there by the heater 16. The warmed washer fluid is supplied to a washer nozzle 80 (FIG. 8) through a hose 56, and ejected toward a wiping region of, e.g., a front window, a rear window or wiper-equipped headlamps. A volume of washer fluid that can be accommodated in the inner space 13 of the heat-retaining hot fluid storage chamber 12 (i.e., a volume of the inner space 13 of the heat-retaining hot fluid storage chamber 12 minus a volume of the small heating chamber 14) is set to be sufficiently larger than a volume of washer fluid that can be accommodated in the inner space 15 of the small heating chamber 14 (i.e., a volume of the inner space 15 of the small heating chamber 14 minus a volume of the heater 16).

The heat-retaining hot fluid storage chamber 12 has a structure similar to that of a vacuum bottle, and as illustrated in FIGS. 2A and 2B, includes a wall 24 having a heat-insulating structure in which a vacuum layer 22 is provided between an inner wall 18 and an outer wall 20. The inner wall 18 is made of, e.g., a metal such as a stainless steel or glass with a vacuum layer 22-side face plated with metal. The outer wall 20 is made of, e.g., a metal such as a stainless steel. A lower end of the heat-retaining hot fluid storage chamber 12 is closed, and the opening 26 is formed at an upper end of the heat-retaining hot fluid storage chamber 12. At an outer periphery of a wall 28 forming the peripheral opening 26, a thread 32 onto which the lid 30 is screwed is provided.

The opening 26 of the heat-retaining hot fluid storage chamber 12 is closed by the lid 30. The lid 30 is made of, e.g., a resin, and as illustrated in FIG. 3A, includes a core 33 and an outer peripheral wall 34 surrounding the core 33 on the lower face side thereof. A groove 36, which opens downward, is formed between the core 33 and the outer peripheral wall 34. An inner periphery of the outer peripheral wall 34 is provided with a thread 38. A sealing rubber (O-ring) 40, which is illustrated in FIGS. 4A and 4B, is accommodated in the groove 36. The sealing rubber 40 is accommodated in the groove 36, the wall 28 of the opening 26 of the heat-retaining hot fluid storage chamber 12 is inserted into the groove 36, and the lid 30 is rotated to screw and firmly fasten the threads 32 and 38 together, whereby the opening 26 of the heat-retaining hot fluid storage chamber 12 is sealed with the lid 30. In such state, the core 33 is inserted in the opening 26.

An electric wire leading channel 44 (FIGS. 3A and 3B) for leading an electric wire 42 (FIGS. 1A and 1B), which supplies power to the heater 16, to the outside is provided on a central axis of the core 33 of the lid 30. The electric wire leading channel 44 can be used for leading a lead wire (not illustrated) for a temperature sensor (not illustrated) for detecting a temperature of the washer fluid in the inner space 15 of the small heating chamber 14 to the outside. Furthermore, the core 33 has a washer fluid inflow channel 46 that allows the washer fluid to flow into the heat-retaining hot fluid storage chamber 12 from the outside, and a washer fluid outflow channel 48 that allows the washer fluid in the small heating chamber 14 to flow out to the outside. The washer fluid outflow channel 48 opens upward in the small heating chamber 14, and thus, even if there is no longer washer fluid in the washer tank 72 (FIG. 8), the small heating chamber 14 is prevented from becoming empty inside, enabling the heater 16 to be prevented from heating the small heating chamber 14 in an empty state. At an upper face of the lid 30, hose connection ports 50 and 52, which communicate with the washer fluid inflow channel 46 and the washer fluid outflow channel 48, respectively, are protrudingly formed. The hoses 54 and 56 (FIG. 1A) are inserted into and thereby connected to the hose connection ports 50 and 52.

The round bar-shaped heater 16 (FIGS. 1A and 1B) is secured to a lower face of the lid 30 on a central axis of the lid 30. The heater 16 includes, e.g., an electrical heating wire-used heater or a PTC ceramic heater enclosed in a cylindrical casing such as a metal pipe or a ceramic pipe. Use of what is called an auto heater with a temperature sensor included therein, which has a temperature control function, as the heater 16 eliminates the need to separately install a temperature sensor in the small heating chamber 14. The small heating chamber 14 is secured to the lower face of the lid 30 in a state in which the heater 16 is housed in the inner space 15 thereof. As illustrated in FIGS. 5A and 5B, the small heating chamber 14 includes a cylindrical member. The small heating chamber 14 has a moderate thermal conductivity, and has a non-heat-insulating structure (a structure including no vacuum layer) made of a material such as a resin, e.g., a hard vinyl chloride resin, ceramics or a metal. An upper end 14 a of the small heating chamber 14 is occluded by the lower face of the lid 30, and a lower end 14 b thereof is bonded to and thereby occluded by a discoid lower lid 58 (plate material in which throttle port(s) is(are) formed), which is illustrated in FIGS. 6A and 6B. The lower lid 58 can be made of a material similar to that of the small heating chamber 14 (e.g., a resin, ceramic or a metal). A plurality of throttle ports 60 is formed in the lower lid 58. The washer fluid in the inner space 13 of the heat-retaining hot fluid storage chamber 12 flows into the inner space 15 of the small heating chamber 14 through the throttle ports 60.

A discoid movable throttle lid 61 is housed in the inner space 15 of the small heating chamber 14. The movable throttle lid 61 is made of a material, such as a hard vinyl chloride resin, having a specific gravity that is somewhat larger than that of the washer fluid. As illustrated in FIGS. 7A and 7B, the movable throttle lid 61 has a discoid shape, and includes a circular central hole 62 formed at a center thereof. The movable throttle lid 61 has an outer diameter that is somewhat smaller than an inner diameter of the small heating chamber 14, and the central hole 62 has an inner diameter that is somewhat larger than an outer diameter of the heater 16. The movable throttle lid 61 is housed in the inner space 15 of the small heating chamber 14 as a result of the heater 16 being inserted into the central hole 62, and is thereby arranged so that the movable throttle lid 61 can freely ascend/descend along the heater 16.

FIG. 8 illustrates an electrical system and a washer fluid feeding system where the warming device 10 with the above-described configuration is added to an existing washer apparatus. FIG. 8 illustrates a case where temperature control is performed using a mechanical sensing-type temperature sensor including a bimetal or a shape-memory alloy, which is installed, e.g., inside the small heating chamber 14 of the warming device 10. The part surrounded by a dotted line is a part added to an existing washer apparatus in order to use the warming device 10. The heater 16 and a washer motor 76 are driven using a battery 63 as a power supply. In other words, the heater 16 and the mechanical sensing-type temperature sensor 64 are serially connected to the battery 63 via an ignition switch 66 and a relay switch 68. The mechanical sensing-type temperature sensor 64 includes a switch (mechanical thermostat) including a moving contact made of, e.g., a bimetal or a shape-memory alloy, and turns the switch on when a temperature of the washer fluid in the small heating chamber 14 is equal to or lower than a set temperature (for example, 60 deg C.), and turns the switch off when the temperature exceeds the set temperature. A timer circuit 70 is provided to turn the relay switch 68 on/off, and in order to suppress power consumption when ignition is started (i.e., when a cell motor is driven), the relay switch 68 is kept in an off state until a predetermined period of time (for example, several seconds) elapses from the ignition switch 66 being turned on, and after the elapse of the predetermined period of time, the relay switch 68 is kept in an on state until the ignition switch 66 is turned off. The washer tank 72 is charged with a washer fluid. Upon a washer switch 74 being turned on via an operation by, e.g., a driver, power is supplied to the washer motor 76, and consequently, the washer pump 78 is driven, whereby the washer fluid in the washer tank 72 is supplied to the warming device 10 through the hose 54. The washer fluid warmed in the warming device 10 is supplied to the washer nozzle 80 through the hose 56 and ejected.

FIG. 9 illustrates an operation of the warming device 10. Respective steps (1) to (4) will be described.

(1) A state in which the washer switch 74 (FIG. 8) is on is illustrated. A washer fluid 82 fed from the washer tank 72 is injected to an upper space inside the heat-retaining hot fluid storage chamber 12 via the hose 54. Consequently, the washer fluid 82 in the heat-retaining hot fluid storage chamber 12 descends and flows into the small heating chamber 14 from the throttle ports 60 of the lower lid 58. Here, the movable throttle lid 61 in the small heating chamber 14 is pushed up by the inflowing washer fluid 82. Consequently, the warmed washer fluid 82 on the upper side of the movable throttle lid 61 is discharged from the warming device 10 via the hose 56 and ejected from the washer nozzle 80. (2) Upon the washer switch 74 being turned off, the supply of the washer fluid 82 from the washer tank 72 is stopped. Consequently, the movable throttle lid 61 descends by means of its own weight. Here, the washer fluid 82 on the lower side of the movable throttle lid 61 moves to the upper side of the movable throttle lid 61 via a gap 84 between an outer periphery of the movable throttle lid 61 and an inner periphery of the small heating chamber 14. (3) Since the power supply to the heater 16 is continued, the washer fluid 82 in the small heating chamber 14 is warmed. Since the small heating chamber 14 has a small volumetric capacity, even if an output of the heater 16 is relatively small (that is, a relatively small current of, for example, around five amperes), a temperature of the washer fluid 82 in the small heating chamber 14 can quickly be increased. Furthermore, here, the movable throttle lid 61 occludes the throttle ports 60 of the lower lid 58 as a result of landing on the lower lid 58, enabling the warmed washer fluid 82 in the small heating chamber 14 to be prevented from flowing out to the inner space 13 of the heat-retaining hot fluid storage chamber 12 through the throttle ports 60. Upon the washer fluid 82 in the small heating chamber 14 being warmed and the washer switch 74 being turned on again, the warmed washer fluid 82 is supplied to the washer nozzle 80 through the hose 56 and ejected again through step (1) above. (4) If the washer switch 74 is left off in step (3) above, heat of the washer fluid 82 in the small heating chamber 14 is conducted to the washer fluid 82 in the heat-retaining hot fluid storage chamber 12 by means of thermal conduction via a wall of the small heating chamber 14, whereby the washer fluid 82 in the heat-retaining hot fluid storage chamber 12 is warmed. When the temperature of the washer fluid 82 in the small heating chamber 14 exceeds a set temperature (for example, 60 deg C.) of the mechanical sensing-type temperature sensor 64 (FIG. 8), the mechanical sensing-type temperature sensor 64 is turned off, whereby the power supply to the heater 16 is stopped. Since the heat-retaining hot fluid storage chamber 12 has the heat-insulating structure, the heat of the washer fluid 82 in the warming device 10 is retained even though the power supply to the heater 16 is stopped. If the temperature of the washer fluid 82 in the small heating chamber 14 is decreased to be equal to or lower than a predetermined value, the power supply to the heater 16 is resumed, and thereafter, the power supply to the heater 16 is repeatedly started and stopped until the ignition switch 66 is turned off. When the ignition switch 66 is turned off, the power supply to the heater 16 is also stopped; however, the heat-retaining hot fluid storage chamber 12 has the heat-insulating structure, and thus, the heat of the washer fluid 82 in the warming device 10 is retained for a long time.

Experimental Example

A prototype of the warming device 10 is fabricated, and a temperature increase characteristic of water when the small heating chamber 14 and the heat-retaining hot fluid storage chamber 12 are filled with the water and power is continuously supplied to the heater 16, and a temperature decrease characteristic (heat-retaining characteristic) of the water in the warming device 10 after the power supply to the heater 16 is stopped were measured. The prototype of the warming device 10 was fabricated using the following parts.

Heat-retaining hot fluid storage chamber 12: a body of a commercially-available vacuum water bottle was used as it is.

Lid 30: a lid of the vacuum water bottle used for the heat-retaining hot fluid storage chamber 12 was modified and used.

Small heating chamber 14: a hard vinyl chloride resin tube

Lower lid 58: a hard vinyl chloride resin plate

Movable throttle lid 61: a hard vinyl chloride resin plate

Heater 16: electrical heating wire-used heater (output of 60 watts)

A total amount of the water in the warming device 10 (a sum of amounts of water charged in the small heating chamber 14 and the heat-retaining hot fluid storage chamber 12) was 485 ml, and the small heating chamber 14 has a volumetric capacity of 50 ml. An initial temperature of the water in a temperature increase test (FIGS. 10 and 11) was 14 deg C., and an initial temperature of the water in a heat-retaining characteristic test (FIG. 12) was 60 deg C.

FIG. 10 illustrates changes in temperature of the water in the small heating chamber 14 after the power supply to the heater 16 is started. The table indicates that the temperature of the water reached 85 deg C. or higher approximately five minutes after the start of the power supply. FIG. 11 illustrates changes in temperature increase (increase amount of temperature) of the water in the heat-retaining hot fluid storage chamber 12 (temperature increase from the initial temperature of 14 deg C.). The table indicates that a temperature increase of 70 deg C. or higher occurred 40 minutes after the start of the power supply.

FIG. 12 illustrates changes in temperature of the water in the warming device 10 when the power supply to the heater 16 was left stopped after the temperature of the water in the warming device 10 being made to 60 deg C. Measurements were made for respective cases where an external air temperature was −5 deg C., −10 deg C., −15 deg C., −20 deg C., −25 deg C. and −30 deg C. The table indicates that the temperature of the water after the elapse of about thirteen hours were 27 deg C. for the case where the external air temperature was −5 deg C., and 13 deg C. for the case where the external air temperature was −30 deg C. Accordingly, for example, where a driver starts his/her car up in the morning following a night when he/she returned home by the car, the temperature of the water can still be kept warm, enabling suppression of time and power required for temperature increase at the time of start-up.

Second Embodiment

A second embodiment of the present invention will be described. FIG. 13 is a transparent view schematically illustrating a warming device 86 according to the present embodiment. In the warming device 86, a lid 30 with a small heating chamber 14 and a heater 16 attached thereto is arranged on the lower side thereof to enhance the heat-insulating properties of an upper portion of the warming device 86 in which a washer fluid having a high temperature is accumulated and suppress heat loss from the upper portion, thereby providing further enhancement of the heat-retaining performance. Components that are in common to those of the first embodiment are provided with reference numerals that are the same as those of the first embodiment. The warming device 86 is installed in, e.g., an engine room of a vehicle in such a manner that the warming device 86 is stood upright as illustrated in FIG. 13. The warming device 86 has a structure in which a cylindrical small heating chamber 14 having a moderate thermal conductivity is concentrically housed in an inner space 13 of a cylindrical heat-retaining hot fluid storage chamber 12 having a heat-insulating structure and a round bar-shaped heater 16 is concentrically housed in an inner space 15 of a small heating chamber 14. The heater 16 and the small heating chamber 14 are attached to a upper face of the lid 30, the heater 16 and the small heating chamber 14 are inserted into the inner space 13 from a lower opening 26 of the heat-retaining hot fluid storage chamber 12, and the lid 30 is firmly screwed to a lower portion of the heat-retaining hot fluid storage chamber 12, thereby providing an integrated configuration in their entirety. A washer fluid is fed from a washer tank 72 (FIG. 8) to the inner space 13 of the heat-retaining hot fluid storage chamber 12 through a hose 54, and flows into the inner space 15 of the small heating chamber 14 through throttle ports 60 at a lower end face of the small heating chamber 14, and is warmed there by the heater 16. The warmed washer fluid is sent out to a washer nozzle 80 (FIG. 8) through a hose 56, and ejected toward a wiping region of, e.g., a front window, a rear window or a wiper-equipped headlamp. A volume of washer fluid that can be accommodated in the inner space 13 of the heat-retaining hot fluid storage chamber 12 (i.e., a volume of the inner space 13 of the heat-retaining hot fluid storage chamber 12 minus a volume of the small heating chamber 14) is set to be sufficiently larger than a volume of washer fluid that can be accommodated in the inner space 15 of the small heating chamber 14 (a volume of the inner space 15 of the small heating chamber 14 minus a volume of the heater 16).

An electric wire 42 for supplying power to the heater 16, an inflow pipe (washer fluid inflow channel) 88 for injecting the washer fluid to an upper portion of the inner space 13 of the heat-retaining hot fluid storage chamber 12, and an outflow pipe (washer fluid outflow channel) 90 that allows the warmed washer fluid in an upper portion of the inner space 15 of the small heating chamber 14 to flow out to the outside penetrate the lid 30 and are attached to the lid 30 in a watertight state. A temperature sensor 92 is provided inside the inner space 15 of the small heating chamber 14. A lead wire 94 for the temperature sensor 92 watertightly penetrates the lid 30 and is led to the outside. Instead of providing the temperature sensor 92 independently, what is called an auto heater including a temperature sensor therein and having a temperature control function can be used as the heater 16.

As with the warming device 10 according to the first embodiment, the warming device 86 can be included in the electrical system and the washer fluid feeding system in FIG. 8 and can be used so as to operate as illustrated in FIG. 9. In other words, upon power being supplied to the heater 16, the washer fluid in the small heating chamber 14 is warmed, and heat of the washer fluid is conducted to the washer fluid in the heat-retaining hot fluid storage chamber 12 by means of thermal conduction via a wall of the small heating chamber 14, and the washer fluid in the heat-retaining hot fluid storage chamber 12 is thereby warmed. Upon a washer switch 74 (FIG. 8) being turned on, the washer fluid fed from the washer tank 72 (FIG. 8) is supplied to the upper portion of the inner space 13 of the heat-retaining hot fluid storage chamber 12 through the inflow pipe 88, and descends in the inner space 13 and flows into the small heating chamber 14 from the throttle ports 60 of the lower lid 58. Here, a movable throttle lid 61 in the small heating chamber 14 is pushed up by the inflowing washer fluid. Consequently, the warmed washer fluid on the upper side of the movable throttle lid 61 flows through the outflow pipe 90 from the upper portion of the small heating chamber 14 and is discharged out of the warming device 86 and ejected from the washer nozzle 80 (FIG. 8). The outflow pipe 90, which corresponds to the washer fluid outflow channel, opens upward in the small heating chamber 14, and thus, even if there is no longer washer fluid in the washer tank 72 (FIG. 8), the small heating chamber 14 is prevented from being empty inside, enabling the heater 16 to be prevented from heating the small heating chamber 14 in an empty state. The rest of operation is the same as that of the first embodiment.

Although in the first and second embodiments, the movable throttle lid 61 descends by means of its own weight, as illustrated in an alternate long and two short dashes line in FIGS. 1A and 13, a weak spring 96 is fitted on the heater 16 to exert a biasing force (extending force) of the spring 96 on the movable throttle lid 61, enabling the movable throttle lid 61 to descend by means of the extending force of the spring 96 (or a combined force of the extending force of the spring 96 and the weight of the movable throttle lid 61). Also, although in the first and second embodiments, the washer fluid moves from the lower side to the upper side of the movable throttle lid 61 through the gap 84 between the outer periphery of the movable throttle lid 61 and the inner periphery of the small heating chamber 14 when the movable throttle lid 61 descends, such movement may be made through a gap between the outer periphery of the heater 16 and the central hole 62 of the movable throttle lid 61, or a void separately provided within a face of the movable throttle lid 61, such as a valved hole (the valve is arranged so as to be closed when the movable throttle lid 61 ascends and be opened when the movable throttle lid 61 descends) or a cutout. Furthermore, in the first and second embodiments, a water level sensor can be arranged inside the small heating chamber 14 to supply power to the heater 16 based on the condition that a water level inside the small heating chamber 14 is equal to or exceeds a predetermined value. Furthermore, although in the first and second embodiments, as illustrated in FIG. 8, the existing washer pump 78 that comes with the washer tank 72 is used to feed a washer fluid, if the flow passage has a larger resistance as a result of addition of the warming device, resulting in a washer fluid being not ejected from the washer nozzle 80 with a sufficient force, a washer pump may be added to the warming device to feed a washer fluid by means of, e.g., serial driving of the two washer pumps. 

1. A washer fluid warming device arranged between a washer tank and a washer nozzle in a washer apparatus on board a vehicle, the washer fluid warming device warming a washer fluid sent in from the washer tank and sending the washer fluid out to the washer nozzle, the device comprising: a heat-retaining hot fluid storage chamber including a wall having a heat-insulating structure in which a vacuum layer is provided between an inner wall and an outer wall and including an inner space into which the washer fluid flowing out of the washer tank flows as a result of a washer pump being driven; a small heating chamber including a wall having a thermal conductivity higher than that of the wall of the heat-retaining hot fluid storage chamber, being housed in the inner space of the heat-retaining hot fluid storage chamber, and further including an inner space into which the washer fluid in the heat-retaining hot fluid storage chamber flows as a result of the washer pump being driven; and an electric heater housed in the inner space of the small heating chamber, the electric heater warming the washer fluid in the small heating chamber, wherein the inner space of the heat-retaining hot fluid storage chamber is set to have a size capable of accommodating a volume of washer fluid that is larger than a volume of washer fluid that can be accommodated by the inner space of the small heating chamber; and wherein the warmed washer fluid flowing out of the small heating chamber is supplied to the washer nozzle as a result of the washer pump being driven.
 2. The washer fluid warming device according to claim 1, wherein the heat-retaining hot fluid storage chamber includes an opening that provides communication between an outer space and the inner space thereof; wherein the small heating chamber with the electric heater housed therein is attached to a lid that occludes the opening; and wherein the small heating chamber is inserted into the inner space of the heat-retaining hot fluid storage chamber from the opening and thereby housed in the inner space of the heat-retaining hot fluid storage chamber and the opening is occluded by the lid.
 3. The washer fluid warming device according to claim 2, wherein the lid includes: a washer fluid inflow channel that allows the washer fluid to flow from the outside into the heat-retaining hot fluid storage chamber; a washer fluid outflow channel that allows the washer fluid in the small heating chamber to flow out to the outside; and an electric wire leading channel that allows an electric wire for supplying power to the electric heater to be led to the outside.
 4. The washer fluid warming device according to claim 2, wherein the small heating chamber is formed in a tubular shape extending in a vertical direction; wherein the washer fluid warming device further includes a plate-shaped movable throttle lid housed in the inner space of the small heating chamber; wherein the electric heater has a stick-like shape and is arranged along a central axis of the tubular small heating chamber; wherein the movable throttle lid includes a central hole, and the electric heater is inserted through the central hole and arranged so that the movable throttle lid can ascend/descend along the electric heater, and wherein upon the movable throttle lid being pushed up by the washer fluid flowing in from a lower portion of the inner space of the small heating chamber, the movable throttle lid makes the washer fluid on an upper side of the movable throttle lid flow out of the small heating chamber, and upon the inflow of the washer fluid being stopped, the movable throttle lid descends by its own weight and/or a spring force, and during the descent, the washer fluid on a lower side of the movable throttle lid is moved to the upper side of the movable throttle lid via at least any one of a gap between an inner face of the small heating chamber and the movable throttle lid, a gap between an outer face of the electric heater and an inner face of the central hole of the movable throttle lid, and a void formed within a face of the movable throttle lid.
 5. The washer fluid warming device according to claim 3, wherein the small heating chamber is formed in a tubular shape extending in a vertical direction; wherein the washer fluid warming device further includes a plate-shaped movable throttle lid housed in the inner space of the small heating chamber; wherein the electric heater has a stick-like shape and is arranged along a central axis of the tubular small heating chamber; wherein the movable throttle lid includes a central hole, and the electric heater is inserted through the central hole and arranged so that the movable throttle lid can ascend/descend along the electric heater, and wherein upon the movable throttle lid being pushed up by the washer fluid flowing in from a lower portion of the inner space of the small heating chamber, the movable throttle lid makes the washer fluid on an upper side of the movable throttle lid flow out of the small heating chamber, and upon the inflow of the washer fluid being stopped, the movable throttle lid descends by its own weight and/or a spring force, and during the descent, the washer fluid on a lower side of the movable throttle lid is moved to the upper side of the movable throttle lid via at least any one of a gap between an inner face of the small heating chamber and the movable throttle lid, a gap between an outer face of the electric heater and an inner face of the central hole of the movable throttle lid, and a void formed within a face of the movable throttle lid.
 6. The washer fluid warming device according to claim 4, wherein a bottom of the tubular small heating chamber is occluded by a plate material in which a throttle port is formed, through which the washer fluid in the inner space of the heat-retaining hot fluid storage chamber flows into the inner space of the small heating chamber.
 7. The washer fluid warming device according to claim 5, wherein a bottom of the tubular small heating chamber is occluded by a plate material in which a throttle port is formed, through which the washer fluid in the inner space of the heat-retaining hot fluid storage chamber flows into the inner space of the small heating chamber.
 8. The washer fluid warming device according to claim 4, further comprising a washer fluid flow passage in which the washer fluid flows into the inner space of the heat-retaining hot fluid storage chamber from an upper portion of the heat-retaining hot fluid storage chamber and descends in the inner space of the heat-retaining hot fluid storage chamber, and the washer fluid that has descended flows into the inner space of the small heating chamber from a lower portion of the small heating chamber and ascends in the inner space of the small heating chamber.
 9. The washer fluid warming device according to claim 5, further comprising a washer fluid flow passage in which the washer fluid flows into the inner space of the heat-retaining hot fluid storage chamber from an upper portion of the heat-retaining hot fluid storage chamber and descends in the inner space of the heat-retaining hot fluid storage chamber, and the washer fluid that has descended flows into the inner space of the small heating chamber from a lower portion of the small heating chamber and ascends in the inner space of the small heating chamber.
 10. The washer fluid warming device according to claim 6, further comprising a washer fluid flow passage in which the washer fluid flows into the inner space of the heat-retaining hot fluid storage chamber from an upper portion of the heat-retaining hot fluid storage chamber and descends in the inner space of the heat-retaining hot fluid storage chamber, and the washer fluid that has descended flows into the inner space of the small heating chamber from a lower portion of the small heating chamber and ascends in the inner space of the small heating chamber.
 11. The washer fluid warming device according to claim 7, further comprising a washer fluid flow passage in which the washer fluid flows into the inner space of the heat-retaining hot fluid storage chamber from an upper portion of the heat-retaining hot fluid storage chamber and descends in the inner space of the heat-retaining hot fluid storage chamber, and the washer fluid that has descended flows into the inner space of the small heating chamber from a lower portion of the small heating chamber and ascends in the inner space of the small heating chamber. 